Railway Line in Brunei

Yesterday I mentioned the 1952 Brunei Darussalam Annual Report. Last night I had a closer look meaning that I actually read the book.What intrigued me was the map of Brunei at the end of the book. Two things stand out. One, the road linked from Kuala Belait ended up somewhere in Anduki. And the other end of the road was at Sungai Abang or if I had scanned a bigger section, the other end would be